CD (Compact Disk) is now widely popular as a means for listening to music. Also as a device for recording and regenerating digital audio data, MD (Mini Disk) systems using magneto-optical media are proliferating. In an MD system, music stored on a CD can be recorded/regenerated.
In this way, conventionally music is generally enjoyed by purchasing a medium where music information is recorded as ROM, such as a CD, and the music is listed to, or by recording favorite music on an MD and listening to it.
Another way of enjoying music is playing music on an instrument. To record music played on an instrument and to regenerate it, an external microphone is attached to a recording device, such as an MD, music is played and recorded live, and is regenerated. In this case music played by an individual alone is recorded.
However most music is created by various instruments on which different parts are played, such as an orchestra or a band. Therefore in order for an individual player to play a part in an orchestra or band, such as the case of playing an instrument while listening to a CD, a separate device for recording must be provided to record that playing.
Also the recording device must be operated simultaneously, which is troublesome. In the case of a method of playing an instrument along with music that is being regenerated from a CD and recording it by an external input microphone, the adjustment of the volume balance between the regeneration of the CD and playing is difficult, which makes it extremely difficult to recording good quality music.
Multiple recording is performed to improve such shortcomings when recording music. In multiple recording, different music is recorded on each track of the recording medium, which has a plurality of recording tracks. In other words, music is recorded on the first track in advance, and sound is superimposed and recorded on another track while listening to the music on the first track being regenerated.
For example, a sound of piano is recorded first and a guitar sound is recorded next while listening to the sound of the piano, so that the piano and guitar can be simultaneously regenerated. In order to record while regenerating using a plurality of tracks, or to simultaneously regenerate music on a plurality of tracks, a high-speed and large capacity storage device is required, where for the most part a hard disk is used.
A multiple recording system using a hard disk which is aimed at producing music, however, requires advanced editing and demands complicated operation. Therefore a multiple recording system using a hard disk is used by a limited number of people, and is not commonly used as yet. Also a magnetic recording medium has no ROM section, such as the phase pits of an optical disk, so in order to record music, the music must be magnetically recorded for each disk, which increases the manufacturing cost.
As a medium which can be more easily handled than a hard disk, a multiple recording system using an MD (Mini Disk) has been implemented. Using an MD makes the medium less expensive, but the user must record music sequentially on a plurality of tracks, which is still the same as a device using a hard disk.
Also in order to record music information in advance before shipment, magneto-optical recording is required for each disk, just like the case of a hard disk, which increases the medium cost. Another problem is that recording capacity decreases because a plurality of tracks are used. Therefore a conventional multiple recording system using an MD for recording as well is used only by some specialists and not the general public.
As mentioned above, the conventional ways of enjoying music are limited to three: listening to music, playing music alone and recording and regenerating music alone, excluding some specialists.
A method of using a concurrent ROM/RAM medium, on the other hand, is a method of having the potential to implement multiple recording and simultaneous regeneration functions, which have been limited to some specialists at low cost.
For example, in Japanese Patent Application Laid-Open No. H7-65375, a method for using a medium comprising ROM and RAM, where music or image information is recorded on the ROM section formed by phase pits in advance, other music or image information is recorded in the RAM section at a same position as the recorded position of the ROM data with synchronizing with the regeneration of the music or image recorded in the ROM, was proposed.
In actual music recording however it is difficult to record RAM data at a same position as the recording position of the ROM data.
The first reason is that there is no means to know the timing to start playing an instrument. Generally each player of an instrument must start playing at the respective correct timing using a timing count means, such as a conductor. However in the case of multiple recording while regenerating music or an image of ROM, the recording side cannot know the timing, and the timing to start playing delays.
The second reasons is that the time delay is generated until the sound information reaches from the speaker to the player or singer in the case of playing a piano or guitar, or singing while listening to music output from a speaker by regenerating the ROM section of the medium. This delay becomes more obvious as the distance between the speaker and the player increases. Also the positional relationship between the sound source, such as a speaker, and the player or singer is not predetermined but is freely set by the user. Therefore it is difficult to perfectly align the position of the music in the ROM section and the recording position in the RAM section at recording.
This is not restricted to music, but is a common problem more or less for other content, such as images. Therefore it is necessary to implement a means for controlling displacement even if the positions of the ROM data and the corresponding RAM data deviate, or performing simultaneous regeneration even if displacement occurs.